Metal honeycomb catalyst supports have been proposed for converters for automobiles. One way to make a metal honeycomb is to lay a corrugated strip of metal on a flat strip of metal, and to wind the two strips upon themselves to make a spiral. Spiral-wound converters have a fatal shortcoming when they are used for automobile converters: they telescope outwardly under the pulsating flow of the engine exhaust. A method that has been used to prevent the telescoping consists of brazing together the layers of the spiral over a short length of spiral, at both ends of the spiral. This method is expensive, and in addition, it restricts the metal alloy of the spiral to metals that can be brazed. Such alloys do not always make satisfactory catalyst supports.
Another way to make a honeycomb is to fold a strip of metal back and forth upon itself. My U.S. Pat. No. 4,402,871, the disclosure of which is incorporated by reference herein, describes such a honeycomb. The face of the honeycomb can have any shape such as a circle or an ellipse, which is commonly used for automobile converters. These folded honeycombs must be anchored in place in their metal shells, called canisters. One method of anchoring the honeycomb is to crimp the end of the canister over the face of the honeycomb. It is easiest to form a crimp on a small circular canister, more difficult on a large circular canister, and most difficult on a canister having an elliptical shape.
This invention provides a simple structure for a catalytic converter, wherein the folded honeycomb is firmly anchored within the canister. The disclosed structure also is adapted to high speed mass production.